Sen. Marco Rubio, R-Fla., on Thursday warned of "grave consequences" if U.S. diplomats in Venezuela are harmed.

Venezuelan President Nicolas Maduro on Wednesday ordered U.S. diplomats in Venezuela to leave the country within 72 hours following President Donald Trump's announcement backing opposition leader Juan Guaido as Venezuela's interim head of state.

"If any harm should come to these diplomats from the United States, I want everybody to know that the consequences from this administration, that they'll impose, will be swift and they'll be decisive," Rubio told NBC News' Andrea Mitchell.

"We're going to impose grave consequences on the people responsible for harm. And that should be left very clearly understood. You know, that's not some idle threat. I'm telling you, I can't go any further than that, but I'm telling you, the consequences will be significant," he added. 

Secretary of State Mike Pompeo responded by saying the U.S. does not recognize his authority, ordering the diplomats to stay in place.

"We call on the Venezuelan military and security forces to continue protecting the welfare and well-being of all Venezuelan citizens, as well as U.S. and other foreign citizens in Venezuela," Pompeo said Wednesday night. "The United States will take appropriate actions to hold accountable anyone who endangers the safety and security of our mission and its personnel."

Maduro earlier in the day threatened to shut off electricity to the U.S. embassy.

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